Filing Details

Note:  Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits.  See §240.13d-7 for other parties to whom copies are to be sent.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

This Amendment No. 1 (“Amendment No. 1”) to Schedule 13D amends and restates the statement on Schedule 13D originally filed on November 29, 2017 relating to the common shares, $0.001 par value (the “Common Stock”), of X4 Pharmaceuticals, Inc. (f/k/a Arsanis, Inc.) (the “Issuer”) having its principal executive office at 955 Massachusetts Avenue, 4^th Floor, Cambridge, Massachusetts 02139.

Certain terms used but not defined in this Amendment No. 1 have the meanings assigned thereto in the Schedule 13D.  Except as specifically provided herein, this Amendment No. 1 does not modify any of the information previously reported on the Schedule 13D.

KNOW ALL MEN BY THESE PRESENTS, that the undersigned hereby constitutes and appoints Louis S. Citron, Timothy Schaller, Sasha Keough and Stephanie Brecher, and each of them, with full power to act without the others, his or her true and lawful attorney-in-fact, with full power of substitution, to sign any and all instruments, certificates and documents that may be necessary, desirable or appropriate to be executed on behalf of himself as an individual or in his or her capacity as a direct or indirect general partner, director, officer or manager of any partnership, corporation or limited liability company, pursuant to section 13 or 16 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), and any and all regulations promulgated thereunder, and to file the same, with all exhibits thereto, and any other documents in connection therewith, with the Securities and Exchange Commission, and with any other entity when and if such is mandated by the Exchange Act or by the Financial Industry Regulatory Authority, granting unto said attorney-in-fact full power and authority to do and perform each and every act and thing necessary, desirable or appropriate, fully to all intents and purposes as he or she might or could do in person, thereby ratifying and confirming all that said attorney-in-fact, or his or her substitutes, may lawfully do or cause to be done by virtue hereof.